In the so-far used semiconductor laser devices made from GaAs based semiconductors, extension of the lifetime of a laser device is achieved due to formation of a window structure where a protective film is formed on end faces of a resonator in the laser device. Similarly, in a nitride semiconductor of a nitride semiconductor laser device, end faces of a resonator are obtained by means of RIE (Reactive Ion Etching) or cleavage, which makes energy gap of end faces narrow, resulting in absorption of light and heat generation on the end faces that leads to impairment of the lifetime in making high-output type, i.e. over 100 mW, lasers. Therefore, it has been suggested that the window structure in nitride semiconductor laser device should be obtained by way of forming a protective film with an AlGaInN semiconductor film (Japanese Patent Application No. 7-249830) and with a different film such as AlN etc. (Japanese Patent Application No. 2002-26442).